THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

[11:30:00] JOHN BERMAN, CNN ANCHOR: Do you see a wave of first-time voters coming to the caucuses tonight? Is that something you've observed?

DONNA BRAZILE, CNN POLITICAL COMMENTATOR: First of all, I gave Carson some love. I want that on the record. He's not dead. He's fading, but he can come back. He might wake up tonight.

Last year, in 2015, you had about 35,000 new registrations, 19,000 for the Republicans, 16,000 for the Democrats. There's no question Sanders and Trump are trying to turn the crowds into first-time caucus goers. There's only one candidate in the history of this caucus that has achieved that, and that was Barack Obama in 2008. Will Iowans show up? The good news is this state as a progressive registration policy. If you have your I.D., all the rest of the stuff, you can show up and register to vote in the Republican or Democratic caucus. There's an opportunity for them to bring in first-time caucus goers. If you're 17 and a half, you can -- and you turn 18 before November, you can also show up tonight and caucus for the Democrats or the Republicans.

KATE BOLDUAN, CNN ANCHOR: What we've establish is we have been promoting underage drinking when we hang out with Ana. This is inappropriate.

(LAUGHTER)

(CROSSTALK)

BRAZILE: I'm saying you can vote. This is an opportunity to shape American history. What a great opportunity we have in the state of Iowa. We know the Iowans pay a lot of close attention to the candidates. Show up tonight. Let your voice be heard.

NAVARRO: The Iowans are the most remarkable people. When I think about it, how they get overrun by overzealous political and media people and all these type of political folks every four years, we take over this place, and they are the most gracious, hospitable --

BRAZILE: Loving people, yeah.

NAVARRO: --, loving, helpful people in America.

(CROSSTALK) NAVARRO: So folks, let me tell you this. Come visit Iowa.

BERMAN: Yay, Iowa. On that note --

BOLDUAN: I heart Iowa.

BRAZILE: And there's nothing better than a pork chop in this state.

(CROSSTALK)

BERMAN: Ana Navarro, Donna Brazile, thank you.

(CROSSTALK)

BRAZILE: Let's get a pork chop and a cold one.

(CROSSTALK)

NAVARRO: Yes.

BERMAN: OK, One Iowa power player says he has more than a few reasons why he thinks Hillary Clinton should be the next president. He's actually won the Iowa caucuses before. Former Iowa Senator, Tom Harkin, joins us live.

BOLDUAN: Also ahead, Donald Trump unleashing a new attack against Ted Cruz ahead of the big contest calling his rival a total liar and repeating his claims that nobody likes him. We're going to talk to one of Cruz's top supporters, Congressman Steve King, of Iowa, coming up.

(COMMERCIAL BREAK)

[11:31:52] BERMAN: John Berman and Kate Bolduan in Des Moines, Iowa, right now. Just a few hours to go until voters line up, go to their caucus sites and cast their first votes of 2016.

This is Waterloo where Donald Trump will hold a rally in a few minutes. He's trying to seal the deal. He's leading in the polls. Will this last-minute push from Trump work?

BOLDUAN: Joining us to discuss what Hillary Clinton and all the candidates need to do to pull off a win tonight, former Iowa Senator Tom Harkin. He's been stumping for Hillary Clinton. He warmed up the crowd last night before Clinton came out to try to close the deal with Iowa voters.

Also, we should note one of the only people you'll see on the set who has won the Iowa caucuses.

Senator, great to see you. Thank you for being here.

TOM HARKIN, (D), FORMER IOWA SENATOR: Thanks for reminding me that I won it.

(LAUGHTER) BOLDUAN: You know better than most --

BERMAN: Anyone.

BOLDUAN: We'll say than anybody. What are you watching for? What are you looking for tonight?

HARKIN: Well, first of all, how many show up before 7:00, the cut-off time. That's the cut off time. And we'll get reports in from around the state. Secondly we'll have reports since I'm a Hillary supporter, we'll have reports from the precinct captains as to how many delegates showed up by 7:00. That's the first thing and how broadly based it is. There are over 1,000 precincts in Iowa. Hillary has a precinct captain in every one. That shows you the depth of the operation here. We'll be looking for that, and we'll be biting your fingernails waiting for the first reports to come back as to how the delegates split.

BERMAN: Let me ask you about the first-time voters. The high-water mark for Democrats, 239,000, was in 2008 for Barack Obama. Nothing else has been close. Where do you see this number this year? Do you think there are first-time voters out there that could push things toward Sanders?

HARKIN: That's possible, but you have to understand when Obama ran and got all the high numbers, it was an earlier caucus, and all of the students were home. They weren't in school. And the Sanders campaign, I noticed just lately has been asking students to go home to vote. Don't vote on the campus. So what that means to me is that you will not have the kind of turnout supporting Sanders as you did for Barack Obama at that time. They will be bunched up.

BERMAN: Clumping. Clumping is what they call it.

HARKIN: There will be clumping in the university campuses.

BOLDUAN: Senator, you and your wife, Ruth, took the stage last night to warm up the stage for Hillary Clinton. As part of that, you tipped off a top-10 list the crowd loved, the top-10 reasons Hillary Clinton will be president. If things don't go your way tonight, what will be the one reason why -- what went wrong?

[11:39:57] HARKIN: I don't think anything went wrong. I think Hillary has run an exceptional campaign here. She's been highly motivating. She's energized crowds. We've had this great organization. It's just that, you know, if Sanders wins, then I would think that it's only because his young people turned out around the state and he was able to get more out than Hillary.

BERMAN: That's the secret sauce for him?

HARKIN: It is, but I, honestly, I don't see that happening.

And I will tell you one thing. I just picked up over the last few days a lot of people that -- remember when Howard Dean ran? "Dance with Dean, but married Kerry?" I think there's a lot of people who have maybe sided with Sanders but now they're thinking wait a minute, who can win? Who's the best qualified person to be the Democratic candidate? And I see a movement sliding back to Hillary.

BERMAN: You served with both Hillary Clinton and Bernie Sanders.

HARKIN: Yeah.

BERMAN: Talk to me about your impressions of sanders as a Senator.

HARKIN: Sanders was a great Senator. He was on my committee. We did a lot of work together. The same with Hillary. She was a wonderful Senator, and she had an ability to work with Republicans and move things along. I think Bernie is more of a motivator and always prodding and pushing. Hillary was a little bit more quiet, let's work and get things, how do you move the ball forward and get something done.

BOLDUAN: Senator, if they're both great, both better than any Republican option, what's wrong with Sanders?

HARKIN: I would be comfortable with Bernie anywhere. L love Bernie Sanders. I love Jane, his wife. They're dear friends of ours. I think at this time and place and because of her experience, background and knowledge, this is Hillary's time. I saw a guy at the Cedar Rapids deal the other day. He had a sign, and it said, "227 years of male presidents is enough. It's time for a woman president of the United States."

BERMAN: Senator Tom Harkin, great to have you here with us. Always a pleasure.

HARKIN: Thank you.

BERMAN: You were the winner.

BOLDUAN: A winner.

(CROSSTALK)

BERMAN: come back and we'll tell people again.

HARKIN: Thanks for reminding me. I think some of these people may have missed when I ran.

(LAUGHTER) BOLDUAN: Thanks for coming on.

HARKIN: Thanks.

BOLDUAN: Coming up, nobody likes him, that's what folks say, and he's also a total liar. That's a sample of Donald Trump's attacks of recent against Ted Cruz. As we close in on this first presidential contest, a top-10 Cruz supporter, Congressman Steve King, of Iowa, will be joining us live.

BERMAN: And speaking of Donald Trump, he is about to take the stage in Waterloo, Iowa. You can see there, warming up the crowds. That's very interesting. These are Trump supporters explaining to people how and where to get to their caucus site tight. It's about getting the machinery working.

We'll be right back.

(COMMERCIAL BREAK)

[11:47:26] BERMAN: All right. John Berman with Kate Bolduan in Des Moines, Iowa. On the left-hand side of your screen is Rubio in Ankeny, Iowa. That is the campaign headquarters for Rubio in this state.

BOLDUAN: With his children? I can't see his wife there but you can see his kids.

BERMAN: He's there and thanking supporters.

SEN. MARCO RUBIO, (R), FLORIDA & PRESIDENTIAL CANDIDATE: See so many people here calling and working. Some of you have been here from other parts of the country, some have taken off work, some have been here since Friday, Thursday, Wednesday and long, giving up your time for this effort. I've done what you're doing for other candidates. I know how much work it was. The first campaign I was involved in was Dole. I started as a volunteer. And this one is going to turn out better than that one but --

(LAUGHTER)

And he's a fine man. I am grateful. I came from the grass roots. I know how much hard work that is, and I appreciate it from the bottom of my heart. I'm also grateful and honored by it.

Maybe some of you I've never met or only one time, and they dedicate came to this cause. I want you to be proud of the fact you worked for us. And everything that I do, I want you to be proud, and I want to make sure I ensure that you're always proud you supported me.

I also think your efforts will be meaningful. I feel positive about what's happening in Iowa and around the country. I see it and I sense it in the work we've done, especially over the last week. I don't think that's a coincidence. We've done things that have helped but you've done it. You're going to help us tonight get people who want to vote for me to vote for me. Tonight, because of the work you've done and are doing, there are people who may not have gone to a caucus because they wanted to watch something on TV. Instead they'll go because you're convincing them it's that important.

And it is important. This election is not just an election. It's not just a choice between two political parties. It is a referendum on our identity as a nation and people. That is what you are participating in. A referendum on what kind of country America is going to be in the 21st century. Your work is not just about electing me. It's about ensuring that this country remains a great country to our children and grandchildren and my children inherit a country as great, if not greater than the one left to us by our parents.

BERMAN: That's Marco Rubio at his Iowa state campaign headquarters thanking all his supporters and staff, and noting his first job in politics was as a volunteer for Bob Dole in 1996. Bob Dole won here that year. I don't think Rubio is going to do better than Bob Dole in Iowa.

BOLDUAN: We'll see.

Let's discuss this. Let's bring in a man who knows Iowa politics well, Congressman Steve King. He is a supporter of Ted Cruz. We've spoken to him many times.

Congressman, it's great to see you.

You didn't have a chance to hear because you were just sitting down.

Marco Rubio is talking about how grateful and he wants to make all of them proud that they are part of something -- part of something bigger. This goes beyond Iowa. It goes beyond -- what is this moment like in those headquarters for Ted Cruz's campaign, for the Marco Rubio's campaign, and all the people that have been working so hard for them?

[11:50:] REP. STEVE KING, (R), IOWA: That tone and that message is delivered to his workers is just right. They need and deserve to hear that thank you. When they put their head and hearts and their backs into this, a lot working day and night for many candidates, it's true in almost every one of those campaigns that left of dedication You want to wrap things up and say thank you. It's always good to do that before the tally is in.

(LAUGHTER)

You know, Marco is doing that.

(CROSSTALK)

BERMAN: They may not be there is the tallies come in the wrong way. That's the truth in politics.

(CROSSTALK)

BERMAN: A little bit of a different tone when candidates talk about each other. Yesterday, Trump, leading in most polls, called Senator Ted Cruz -- who you're working for -- flat-out called him a liar. You're response?

KING: Well, where I come from, them's fighting words. You know, when you say that, you better be able to make it stick. I don't know what it was he was talking about, but I can tell you I've spent at least two weeks on the bus with Ted Cruz, and that's fairly early in the morning until way late at night. I have watched him before -- in front of the stage, behind the curtain with his family. I watched him make decisions on the fly. There's not been one single moment that I had even an ounce of regret, and I think people know what I think of principle and truth and constitutional values. I watched how Donald Trump turned his campaign into something that looks like the WWE to me. It's more than that. This is not world wrestling here. This is about the leadership of the free world. I think we have a higher level of dignity and a higher level of restrained. Even if he thinks that, he should find another way to make that kind of a statement.

BOLDUAN: We had Senator Tom Harkin here just a moment ago, and he said very clearly, on the Democratic side, shocker, everybody, it comes down to turnout. On the Republican side, shocker, it's going to come down to turnout. You know this very well. What is in your view the tipping point? The more first-time caucus goers, that's going to benefit Donald Trump. Where is the tipping point for you?

KING: I picked a number that -- I just put this down, 135,000 Republicans. If that number goes above that substantially, it gives Donald Trump an advantage. If that number is below that, it gives Ted Cruz an advantage. That's how we measured it.

But I will say that well over two-thirds of the caucus goers are full- spectrum constitutional Christian conservatives, and that fits Ted Cruz more than any candidate I remember seeing before coming to the Iowa caucus. But we've never seen a showman like Donald Trump. That's what you have, the unknown factor, can he get a lot of people to come to caucus that have never gone before, and that's stacking against something. Sometimes it's three generations of a family that will walk into a church or gymnasium or home and put up their votes, and they've been out there working a long time. Thousands of volunteers doing this.

I also want to take the opportunity just to congratulate everybody that's throwing their head and heart into this. As somebody mentioned the other day, and just a little earlier this morning, that it was compared to the Super Bowl. I'm happy with that. But it's bigger than the Super Bowl.

BOLDUAN: Don't bring that up to this guy.

(LAUGHTER)

(CROSSTALK)

BOLDUAN: Congressman, it's great to see you.

KING: Great to see you.

BOLDUAN: We'll see how it turns out tonight. We'll talk to you soon. KING: Appreciate it.

BOLDUAN: Thanks so much.

BERMAN: I want to switch gears and talk about the Democratic side of the race, and talk to someone who knows a lot about how to run a Democratic race in this state, CNN political commentator, Dan Pfeiffer, who was a key advisor to Senator Barack Obama back in 2008 when he won here.

Dan, thanks so much.

DAN PFEIFFER, CNN POLITICAL COMMENTATOR: Hey, guys.

BERMAN: Our question to you, six or seven hours before caucus time, when do you know -- when did you know this was breaking your way?

PFEIFFER: Caucus day is the weirdest of all Election Days. It doesn't start until nighttime. Normal Election Day, you see turnout models. You can tell which precincts that matter to you, how high turnout or low turnout. You can do things like redirect robo calls or do media to try to amp up turn out where you are down. Caucus day, you just wait all day long for it to actually happen. It's the hardest of all election days.

In 2008, maybe we were naive, but we were incredibly confident going in because we knew we had this incredible operation. We had run the numbers. We checked them. We had well surpassed our internal numbers, benchmarks, which we knew we needed to get to win. We were very confident. You know, when we lost New Hampshire a few weeks later -- Iowa was the last time I was ever confident on Election Day.

(LAUGHTER)

In this case, you won't actually know until the results start coming in.

[11:55:13] BOLDUAN: We will see, Dan.

Remember, on the Republican side last time around, that went for two weeks?

BERMAN: Well, Mitt Romney won caucus night --

BOLDUAN: Until he didn't.

BERMAN: -- until he didn't.

(CROSSTALK)

BERMAN: It was like, thanks a lot, guys.

(LAUGHTER)

Dan Pfeiffer, great to have you with us.

BOLDUAN: Thanks, Dan.

BERMAN: Thank you so much.

PFEIFFER: Thank you.

BERMAN: Just a reminder, moments from now, Donald Trump is going to take the stage. He is in Waterloo, Iowa. He is making his final pitch to voters. We will bring you there the second it happens. Be right back.